1. Field of the Invention
The present invention relates to a transfer medium suitable for use in forming an image on a printing medium by transfer printing, a transfer printing process using this image-transfer medium and a transfer printing cloth, and more particularly to an image-transfer medium for ink-jet printing in which an ink-jet printing system is used upon forming an ink image on a transfer layer thereof, a transfer printing process in which such an image-transfer medium is used to transfer the image formed on a transfer layer to a portion of a cloth, thereby forming an image on the cloth, and a cloth having the transferred image formed by the transfer printing process.
2. Related Background Art
An ink-jet printing method is a printing method in which printing is conducted by generating and ejecting droplets of an ink by one of various ink ejection systems, for example, an electrostatic attraction system, a system in which a piezoelectric element is used to give an ink mechanical vibration or change, or a system in which an ink is heated to form bubbles in the ink, thereby using the pressure thus produced, and applying the droplets in whole or in part to a printing medium. The ink-jet printing method attracts attention as a printing system which scarcely produces noise and can conduct high-speed printing and color printing.
In recent years, ink-jet printers, by which color printing can be simply conducted as described above, have been spread, and there has thus been an increasing demand for conducting color printing on various media, particularly, cloth, using these printers. In particular, a printing method using an image-transfer medium is very effective in that printing can be conducted irrespective of the forms of printing media, namely, the formation of an image can be performed on any medium which cannot be directly printed by a printer, so that it is possible to conduct printing on a cloth after subjecting to sewing or a large-sized cloth.
As processes in which an image-transfer medium making good use of an ink-jet technique is used, Japanese Patent Application Laid-Open Nos. 58-215392 and 58-222878 have proposed processes for printing an image on a transparent film. The former process is a heat transfer printing process in which an image is formed on a colorless transparent base paper sheet coated with a coating agent, and a transparent film is then laminated on the paper sheet to heat-transfer the image to the film. Accordingly, this process is a process of transferring the image by heat-fusing the film which is a transfer-printing medium. Therefore, this process cannot be applied to transfer-printing media having no heat fusibility. Japanese Patent Application Laid-Open No. 2-295787 has proposed a process in which a swelling layer is provided on a base material, an image is formed on this swelling layer, and the image is transferred to a cloth by heating it from the side of the base material, and a transfer-printing medium used in this process. However, dyes usable in the formation of the image in this proposal are sublimate dyes, so that it cannot be applied if an image-transfer medium is formed of natural fiber such as cotton. Japanese Patent Application Laid-Open No. 62-140879 discloses an image forming process in which an image is formed on a transfer-printing medium having a surface layer having high liquid permeability and fusibility and an ink-retaining layer, and the surface layer of the transfer medium is brought into contact with a medium to be transferred, thereby fuse-bonding the surface layer, and a printing medium. According to this process, it is possible to transfer the image to cloth, but the process involves a problem that since the image is formed on the ink-retaining layer composed mainly of a water-soluble polymer, the transferred image transferred to the cloth is poor in resistance to water and the like.
Japanese Patent Application Laid-Open No. 62-170383 has proposed a printing medium of constitution similar to the present invention though its object is different from that of the present invention. This printing medium comprises a base material and an ink-absorbing layer composed of fine particles of a thermoplastic resin and a polymeric binder provided on the base material. The thermoplastic fine particles are heated into a transparent film after printing, thereby providing a print having high weather resistance. However, if this printing medium is used as an intermediate transfer medium for cloth, it is difficult to transfer the ink-absorbing layer to the cloth even if heated because adhesion between the ink-absorbing layer and the base material is high, whereby a good image cannot be provided.
With respect to the transfer-printing media making good use of an ink-jet technique for forming an image on cloth, there are various problems to be solved as described above. In particular, the following requirements may be mentioned.
(1) Quality of Image Printed by an Ink-jet System:
First, in order to provide a clear transfer image having high color depth on a printing medium such as cloth, it is necessary to keep an image on an image-transfer medium high quality. Accordingly, image-transfer media for ink-jet printing are required to have such performance characteristics that they can receive inks quickly, that they have high ink absorbing capacity, that the diameters of ink dots formed thereon do not more increase than they need, that they can provide ink dots high in optical density and clear in periphery, and that they can provide ink dots having a substantially round shape and a smooth periphery.
(2) Transferability to Cloth:
In order to provide an image having high color depth after transfer, it is necessary for an image formed on a transfer medium to be efficiently transferred to cloth. Accordingly, image-transfer media for ink-jet printing are required to have good transferability to the cloth and further to permit the formation of an image-forming layer (transfer layer) adapted to cloth because the cloth generally has considerably high stretch properties.
(3) Fastness Properties after Transferred to Cloth:
Performance characteristics required of an image formed on cloth after transfer include fastness properties such as fastness to laundering and fastness to perspiration. In particular, when an image is formed by means of a general-purpose ink-jet printer, it is impossible to select optimum coloring materials for individual fibers among various kinds of fibers. Accordingly, in order to permit a wide variety of formation of images for various kinds of fibers, the image-transfer media for ink-jet printing are required to cause coloring materials to strongly fix to cloth so as to prevent the coloring materials from bleed when a transferred image is wetted with water or perspiration even when the coloring materials have no dyeing property to fiber of the cloth in themselves.
It is therefore an object of the present invention to provide an image-transfer medium making good use of an ink-jet printing technique, which permits the formation of a satisfactory image on cloth, a transfer printing process using this medium and a transfer-printing cloth having an image formed by the transfer printing process, and particularly to provide an image-transfer medium for ink-jet printing, which satisfies the following requirements:
(1) having a transfer layer high in ink absorbency;
(2) permitting the formation of a clear transferred image having high color depth on cloth;
(3) having a transfer layer high in adhesion to cloth and providing a transferred image having good transferability; and
(4) having a transfer layer which exhibits high fastness properties after transferred to cloth.
Another object of the present invention is to provide an image-transfer medium for ink-jet printing, which satisfies the above-described requirements (1) to (4) and permits the simple formation of images on cloth even in homes by means of a general-purpose ink-jet printer, and a transfer-printing process using this medium.
The above objects can be achieved by the present invention described below.
According to the present invention, there is thus provided an image-transfer medium for ink-jet printing, comprising a releasing layer and a transfer layer containing fine particles of a thermoplastic resins and a polymeric binder, provided on a base material, wherein the polymeric binder is a thermoplastic resin.
According to the present invention, there is also provided a transfer printing process comprising ejecting inks on a transfer layer of an image-transfer medium for ink-jet printing, which has the transfer layer provided on a base material, in accordance with an ink-jet printing method to form an image, placing cloth on the image-transfer medium from the side of the transfer layer on which the image has been formed, and heating and pressing the transfer layer from the side of the cloth or the base material to transfer the transfer layer to the cloth, thereby forming an image on the cloth, wherein the image-transfer medium for ink-jet printing is the image-transfer medium for ink-jet printing described above.
According to the present invention, there is further provided a transfer-printing cloth having a transfer image formed by the transfer printing process described above.